Versatile Dehydrogenation of Carbonyls Enabled by an Iodine(III) Reagent

Abstract

We report the utilisation of an iodine(III) reagent to access α,β-unsaturated carbonyls from the corresponding silyl enol ethers of ketones and aldehydes, and from enol phosphates of lactones and lactams....

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Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Versatile Dehydrogenation of Carbonyls Enabled by an
Iodine(III) Reagent†
Bence B. Botlik,a Patrick Finkelstein,a Ann-Sophie K. Paschke,a Julia C. Reisenbauera and Bill
Morandi*a
We report the utilisation of an iodine(III) reagent to access α,β-
unsaturated carbonyls from the corresponding silyl enol ethers of
ketones and aldehydes, and from enol phosphates of lactones and
lactams. The transformation is rapid, scalable, and can be carried
out in one pot, directly dehydrogenating saturated carbonyls.
Converting saturated carbonyl compounds into the
corresponding α,β-unsaturated derivatives is a key trans-
formation in synthetic organic chemistry.1 The products of
these dehydrogenation processes are valuable intermediates
and versatile building blocks in the synthesis of natural products
as well as industrially relevant targets, and ubiquitous
functional moieties in various materials.2,3 The relevance of α,β-
unsaturated carbonyls is particularly reflected by their
abundance among aroma compounds and odorants, thus they
are of special interest for the fragrance industry (Scheme 1A).4
In addition, their important role as useful synthetic
intermediates is showcased by the large number of established
interconversions for these functional handles that further
enable their derivatisation. For instance, conjugate additions,
cross couplings, regioselective α-functionalisations, and alkene
difunctionalisation reactions open different avenues to access a
broad range of products from α,β-unsaturated carbonyls.2,5
Most known dehydrogenation methods formally proceed via
two consecutive chemical transformations. Typically, in the first
step, an enol or an enolate is formed, which is either directly
transformed into the desired unsaturated product, or is trapped
in situ generating the corresponding silyl enol ether. This
strategy allows for the activation of the α-position and controls
the regioselectivity of the subsequent dehydrogenation step
mediated by an oxidant, resulting in the formation of the
corresponding desaturated products. To date, most of the
Entry
Deviation from abovea
Yieldb of 2a (%)
1
None
60
2
MeCN instead of acetone
38
3
THF instead of acetone
43
4
PIDA instead of PIFA
0
5
HTIB instead of PIFA
5
6
KOH instead of NaOAc
59
7
KTFA instead of NaOAc
58
8
Et3N instead of NaOAc
48
9
1 equiv. PIFA
42
10
3 equiv. PIFA
60
11
TIPS instead of TBS
28
a.Laboratorium für Organische Chemie, ETH Zürich, Vladimir Prelog Weg 3, HCI,
8093 Zürich, Switzerland. E-mail: morandib@ethz.ch
† Supplementary Information available.
RR
oxidant
•Compatibility with ester
and amide substrates
B) Transition metal-free α,β-dehydrogenation of carbonyls:
• Iodine(V)
reagents
• Selenium-based
oxidants
• Benzoquinone
derivatives
• Oxoammonium
salts
• Sulfinimidoyl
chlorides
R/H
O
R/H
O
Established oxidants: Less explored:
•Iodine(III) reagents
as oxidants
• Trityl
salts
for X = OR, NR2
for X = H, alkyl
C) This work:
X
O
X
O
PIFA
NaOAc
or
X
O
X
OPOPh
OOPh
Si
Me
Me
tBu
HH
H
H
formation of enolates,
enols, or enol ethers
O
OOO
Nootkatone
grapefruit aromatic
Carvone
peppermint and
caraway aromatic
β-Damascone
rose aromatic
Jasmone
jasmine aromatic
A) Industrially relevant compounds containing an α,β-unsaturated carbonyl moiety:
• O2+
visible light
• Electro-
chemical means
Scheme 1 – A) Relevance of α,β-unsaturated carbonyl compounds B) Previous
examples of transition metal-free carbonyl dehydrogenation C) This work.
OTBS O
PIFA (2 equiv.)
NaOAc (2 equiv.)
acetone (0.125 M)
0 °C, 10 min
then r.t., 30 min
1a 2a
Table 1 – Selected optimisation data for the dehydrogenation of silyl enol ethers via
iodine(III) reagents. a Reaction conditions: silyl enol ether (0.05 mmol), PIFA (0.10 mmol),
NaOAc (0.10 mmol), acetone-d6 (0.125 M), 0 °C, 10 min, then room temperature (r.t.),
30 min. b Yields determined by 1H NMR analysis of the crude reaction mixtures, using
mesitylene as the internal standard.
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developed carbonyl α,β-dehydrogenation reactions employ
transition metals.1,6–15 In contrast, transition metal-free
approaches are comparatively less established. Besides a recent
electrochemical approach,16 other common strategies rely on
the utilisation of oxoammonium salts,17 benzoquinone
derivatives,18 selenium compounds,19 trityl salts20 or
sulfinimidoyl derivatives21 as oxidants (Scheme 1B).
Additionally, methods implementing iodine(V) reagents have
also been reported, both using either silyl enol ethers or the
saturated carbonyls as starting scaffolds.22,23 However, these
methods are often limited in their scopes to the
dehydrogenation of ketones and aldehydes, and commonly
require long reaction times and elevated temperatures.
Methods relying on iodine(III) reagents as oxidants are scarce,
and to date have been restricted to specific systems, such as
the flavanone to flavone transformations,24 and the double
dehydrogenation of cyclic β-ketocarbonyls.25 Moreover, silyl
enol ethers usually exhibit different reactivities with iodine(III)
reagents and in most cases result in the formation of α-
functionalised ketones, commonly generating α-ketoacetate
derivatives,26 α-hydroxyketones,27 α-methoxyketones,28 and α-
sulfonyloxyketones.29
Our group recently disclosed that iodine(III) reagents facilitate
the nitrogen atom insertion into the silyl enol ether of indanone
and related scaffolds in the presence of an external nitrogen
atom source.30–33 Based on these results, similar substrates
possessing silyl enol ether functional handles were investigated
towards their reactivity with iodine(III) reagents. However, a
mechanistically distinct reactivity was observed in various
cases, leading to the formation of the corresponding
dehydrogenation products. This is hypothesised to be the result
of utilising the understudied combination of a particularly
strong hypervalent iodine oxidant and an equivalent amount of
base, with easily oxidisable silyl enol ether reaction partners.
Herein, the optimisation and development of a general, rapid,
and operationally simple iodine(III)-mediated dehydrogenation
method is presented, which grants access to α,β-unsaturated
carbonyls from silyl enol ethers of ketones and aldehydes, and
from enol phosphates of lactones and lactams (Scheme 1C).
Initial optimisation of the transformation was performed using
tert-butyldimethylsilyl-(TBS)-protected cyclohexenol 1a as the
model substrate (Table 1). Acetone was found to be the most
effective solvent for the reaction, with acetonitrile and
tetrahydrofuran (THF) also providing moderate yields of the
dehydrogenation product 2a, while other examined solvents
showed significantly lower conversion to the desired product.
O
O
O
O
OO
CH3
H
O
tBu
O O
O
O
N O
Boc
2d (77%) 2e (69%)
Flavone
Ph
2r (68%)
2n (78%)
Coumarin
(56%)
2j:2j' = 2:1e
Lilial-derived
H
O
H3C CH3
CH3
H
O
KetonesaAldehydesa
EstersbAmidesb,c
2k (72%)
Cinnamaldehyde
Ph
O
Ph
2h (20%)
2a (62%)
(60%)d
2b (61%)d
2p (43%)d
CH3
O
2c (45%)
Exaltone-derived
2l (46%)
63:37 (E:Z)e
Citronellal-derived
2g (68%)
2m (41%)d
N O
Boc
O
X
O
X
O
NaOAc (2 equiv.)
PIFA (2 equiv.)
acetone (0.125 M)
0 °C, 10 min
then r.t., 30 min
H
H
O
CH3
O
MeO
2f (75%)
Nabumeton-derived
O O
H3C
Ph
2o (43%)
N O
Boc
2s (33%)
O
2i
desired product
is not formed
2t
desired product
is not formed
CH2
H
O
tBu
2j 2j'
+
C6H13 OMe
OC6H13 OMe
O
O
CF3
O
+
2q (25%)e2q'(34%)e
C6H13 OMe
OP(O)(OPh)2
H
O
enol formation
for X = OR, NR2
for X = H, alkyl
X
O
X
OPOPh
OOPh
or
Si
Me
Me
tBu
HH
1q
O
P
O
PhO
PhO
Scheme 2 – Substrate scope. The yields are isolated yields of the reaction, unless indicated otherwise. a Silyl enol ethers were used as starting materials. b Enol phosphates
were used as starting materials c The reaction was carried out in acetonitrile instead of acetone d Reaction carried out on 0.05-mmol scale, yields determined by 1H NMR
analysis of the crude reaction mixtures, using mesitylene internal standard. e Isomeric ratios were determined by 1H NMR analysis. For details, see Supporting Information.
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Bis(trifluoroacetoxy)iodobenzene (PIFA) was the most suitable
oxidant, as the use of other, less oxidising iodine(III) reagents
either afforded the desired product in low yields or no product
formation was detected. In addition, various inorganic bases
were found to be compatible with the initial screening
conditions, resulting in nearly identical yields, however, amine
bases reduced the desired reactivity. Using oxidant loadings
lower than 2 equivalents was detrimental to the yield, however,
further increasing the amount of oxidant in the reaction also did
not improve the overall yield. Variation of the silyl groups
incorporated in the starting material indicated the superiority
of the TBS group, as tri-isopropylsilyl (TIPS) enol ethers were
transformed with significantly lower yields, and in general low
reactivity was observed in the case of other silyl groups, such as
tri-methylsilyl and tri-ethylsilyl groups. Finally, the effects of
molarity and temperature were examined, and the highest
yields of product 2a were obtained when the reaction was
performed at 0 °C using a more dilute solution (0.125 M with
respect to substrate 1a in acetone).
With the optimal conditions in hand, we examined the scope of
the transformation (Scheme 2). Cyclic aliphatic ketones 2a and
2b were both obtained in approximately 60% 1H NMR yield,
which corresponds well to the isolated yield of 2a. Similarly,
other silyl enol ethers exhibiting larger ring sizes were also
found to be compatible with the reaction and the macrocyclic
product 2c was isolated in moderate 45% yield. Chromanone
derivatives 2d and 2e were obtained in good yields (77% and
69%, respectively), as well as phenyl-conjugated alkenes,
including 2g and Nabumeton-derived product 2f. In contrast,
chalcone 2h was isolated in lower yield, likely due to the
decomposition of the silyl enol ether under the reaction
conditions, resulting the saturated carbonyl as a major side
product. In the case of indanone 1i, however, the corresponding
dehydrogenation product 2i could not be observed. Aldehyde-
derived starting scaffolds exhibited comparable reactivity to
that of ketone-derived ones. The compatibility of aldehydes
with our method was examined through a number of examples
that are important to the fragrance industry.4 Lilial-derived 2j
and 2j’ were obtained in a 2:1 ratio of regioisomers and were
isolated in a combined 56% yield, whereas cinnamaldehyde 2k
was isolated in 72% yield. Similarly, citronellal 1l transformed
into dehydrogenated product 2l in the presence of another
alkene handle in moderate yield, resulting in the formation of
both the E and Z alkenes in a 2:1 ratio. Finally, the formation of
the desaturated aliphatic aldehyde 2m was also observed. Apart
from ketone and aldehyde substrates, lactones and lactams
were also found to be suitable substrates for the reaction. As
the silyl enol ethers of lactones and lactams are unstable and
prone to hydrolysis, the more stable enol phosphate derivatives
were employed. Coumarin (2n) was obtained in high yield
(78%), while its substituted derivative 2o was isolated in
reduced yield. The desaturation of a non-conjugated aliphatic
lactone could also be achieved, resulting in the formation of
product 2p in 43% 1H NMR yield. When employing an open
chain enol phosphate, the desired product 2q was formed and
co-isolated with the α-trifluoroacetylated side product 2q’.
Additional examples showcasing the reaction´s translation to
enol phosphates derived from lactams were tested and the
corresponding dehydrogenation products 2r and 2s were
isolated in 68% and 33%, respectively. The non-conjugated enol
phosphate 1t, however, did not yield the corresponding
dehydrogenation product 2t.
We hypothesised that the reaction could be carried out in a
one-pot manner directly using the saturated carbonyl
compounds as starting materials, which would greatly improve
the synthetic utility of the developed transformation.
Therefore, we set out to examine the one-pot dehydrogenation
through a representative example of each four carbonyl classes
(Scheme 3A). To our delight, ketone 1d” yielded the desired
product 2d in 51% yield upon using THF solvent for the silyl enol
ether formation step and a THF:acetone = 1:9 solvent mixture
in the subsequent dehydrogenation step. Similarly, the direct
dehydrogenation of carbocyclic ketone 1c” was also
demonstrated. Using the same conditions, aldehyde 1k”
O O O O
LiHMDS
then P(O)(OPh)2Cl
then KTFA, PIFA
conditions ii)
2n (60%)
OTBS
NaOAc (2 equiv.)
PIFA (2 equiv.)
acetone (0.125 M)
0 °C, 10 min
then r.t., 30 min
1k
14 mmol
2k (73%)
1.35 g
A) One-pot dehydrogenation reactions
B) Gram-scale reaction
H
O
1n"
O
Et3N,TBSOTf
then NaOAc, PIFA
conditions i)
2d (51%)
1d"
O
O
O
2c (34%)
O
1c"
H
H
H
H
H
HO
N O NO
LiHMDS
then P(O)(OPh)2Cl
then NaOAc, PIFA
conditions iii)
2r (41%)
1r"
H
H
Boc Boc
2k (48%)
1k"
H
O
H
OH
H
Et3N,TBSOTf
then NaOAc, PIFA
conditions i)
Et3N,TBSOTf
then NaOAc, PIFA
conditions i)
Scheme 3 – Further experiments. A) One-pot dehydrogenation reactions. Conditions: i) Et3N
(1.5 equiv.), TBSOTf (1.2 equiv.), THF (1 M), r.t., 1 h; then NaOAc (2 equiv.), PIFA (2 equiv.),
THF:acetone = 1:9 (0.1 M), 0 °C, 10 min; then r.t., 30 min. ii) LiHMDS (1.0 equiv.), dry THF
(0.125 M), - 78 °C, 30 min; then P(O)(OPh)2Cl (1.0 equiv.), - 78 °C to r.t., 1 h; then KTFA (4
equiv.), PIFA (4 equiv.), r.t., 30 min. iii) LiHMDS (1.1 equiv.), dry THF (0.125 M), - 78 °C, 30
min; then P(O)(OPh)2Cl (1.1 equiv.), - 78 °C to r.t., 1 h; then NaOAc (2 equiv.), PIFA (2 equiv.),
THF:MeCN= 1:1 (0.06 M), 0 °C, 10 min; then r.t., 30 min. B) Scale-up experiment.
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afforded the corresponding dehydrogenation product 2k in 48%
isolated yield. Furthermore, the possibility for the one-pot
dehydrogenation of lactones was demonstrated by using 1n”,
which afforded product 2n in 60% isolated yield. Key to success
was the implementation of THF as the reaction solvent, as it is
compatible with both the enol phosphate formation and the
subsequent oxidation step, alongside using increased amounts
of PIFA and implementing KTFA as the base. By using an
analogous strategy, the dehydrogenation of lactam 1r” also
proceeded in a one-pot fashion to afford dehydrogenated
lactam 2r. These results possess considerable synthetic
importance, as transition metal-free dehydrogenation methods
of lactones and lactams are scarce.1,34 Even though higher
overall yields are observed when using the two-step approach,
the combined yields over the two steps are comparable to the
yields of the one-pot transformation. The scalability of the
reaction was also examined, and the formation of
cinnamaldehyde (2k) was conducted on a gram-scale (14.0
mmol of starting material; Scheme 3B), providing the desired
product in 73% isolated yield, which is identical to the result
obtained for the 1-mmol scale.
In conclusion, we have developed an operationally simple
carbonyl dehydrogenation method, complementing already
existing methodologies for the formation of α,β-unsaturated
ketones, aldehydes, lactones, and lactams, by using a readily
available iodine(III) oxidant under basic conditions.
Furthermore, we have demonstrated the excellent scalability of
the reaction to gram-scale as well as the feasibility of a one-pot
approach to rapidly access α,β-desaturated products directly
from the corresponding saturated carbonyls.
We thank Prof. Ori Green (Technion) for valuable discussions.
This work was supported by ETH Zürich and the Swiss National
Science Foundation (SNSF 184658). B. B. B. and J. C. R.
acknowledge a fellowship from the Scholarship Fund of the
Swiss Chemical Industry (SSCI). A. S. P. acknowledges a
fellowship from the Fonds der Chemischen Industrie (FCI). We
thank the NMR and MS (MoBiAS) service departments at ETH
Zürich for technical assistance and the Morandi group for
critical proofreading of the manuscript.
Conflicts of interest
There are no conflicts to declare.
Data availability
The data supporting this article have been included as part of the
Supplementary Information.†
Notes and references
1 S. Gnaim, J. C. Vantourout, F. Serpier, P.-G. Echeverria and Phil.
S. Baran, ACS Catal., 2021, 11, 883–892.
2 H. Chen, L. Liu, T. Huang, J. Chen and T. Chen, Adv. Synth. Catal.,
2020, 362, 3332–3346.
3 G. P. Rosa, A. M. L. Seca, M. do C. Barreto and D. C. G. A. Pinto,
ACS Sustain. Chem. Eng., 2017, 5, 7467–7480.
4 D. Pybus and C. Sell, The Chemistry of Fragrances, Royal Society
of Chemistry, 2007.
5 S. Patai, The Chemistry of enones, Wiley, 1989.
6 Y. Chen, J. P. Romaire and T. R. Newhouse, J. Am. Chem. Soc.,
2015, 137, 5875–5878.
7 D. Huang, Y. Zhao and T. R. Newhouse, Org. Lett., 2018, 20, 684–
687.
8 M. Chen and G. Dong, J. Am. Chem. Soc., 2017, 139, 7757–7760.
9 M.-M. Wang, X.-S. Ning, J.-P. Qu and Y.-B. Kang, ACS Catal.,
2017, 7, 4000–4003.
10 Y. Shang, X. Jie, K. Jonnada, S. N. Zafar and W. Su, Nat.
Commun., 2017, 8, 2273.
11 M. Chen, A. J. Rago and G. Dong, Angew. Chem. Int. Ed., 2018,
57, 16205–16209.
12 Z. Wang, Z. He, L. Zhang and Y. Huang, J. Am. Chem. Soc., 2018,
140, 735–740.
13 D. Huang, S. M. Szewczyk, P. Zhang and T. R. Newhouse, J. Am.
Chem. Soc., 2019, 141, 5669–5674.
14 Y. Zhao, Y. Chen and T. R. Newhouse, Angew. Chem. Int. Ed.,
2017, 56, 13122–13125.
15 D. Huang, S. M. Szewczyk, P. Zhang and T. R. Newhouse, J. Am.
Chem. Soc., 2019, 141, 5669–5674.
16 S. Gnaim, Y. Takahira, H. R. Wilke, Z. Yao, J. Li, D. Delbrayelle, P.-
G. Echeverria, J. C. Vantourout and P. S. Baran, Nat. Chem.,
2021, 13, 367–372.
17 M. Hayashi, M. Shibuya and Y. Iwabuchi, Org. Lett., 2012, 14,
154–157.
18 E. A. Braude, L. M. Jackman and R. P. Linstead, J. Chem. Soc.
Resumed, 1954, 3548–3563.
19 K. B. Sharpless, R. F. Lauer and A. Y. Teranishi, J. Am. Chem. Soc.,
1973, 95, 6137–6139.
20 M. E. Jung, Y.-G. Pan, M. W. Rathke, D. F. Sullivan and R. P.
Woodbury, J. Org. Chem., 1977, 42, 3961–3963.
21 T. Mukaiyama, J. Matsuo and H. Kitagawa, Chem. Lett., 2000, 29,
1250–1251.
22 K. C. Nicolaou, D. L. F. Gray, T. Montagnon and S. T. Harrison,
Angew. Chem. Int. Ed., 2002, 41, 996–1000.
23 K. C. Nicolaou, Y.-L. Zhong and P. S. Baran, J. Am. Chem. Soc.,
2000, 122, 7596–7597.
24 O. Prakash, S. Pahuja and R. M. Moriarty, Synth. Commun.,
1990, 20, 1417–1422.
25 S.-S. Liu, L. Wang, Y.-N. Duan, A. Yu and C. Zhang, Sci. China
Chem., 2019, 62, 597–601.
26 I. Brunolevskaya, K. Kusainova and A. Kashin, Zh. Org. Khim.,
1988, 24, 358.
27 R. M. Moriarty, M. P. Duncan and O. Prakash, J. Chem. Soc.
Perkin 1, 1987, 0, 1781–1784.
28 R. M. Moriarty, O. Prakash, M. P. Duncan, R. K. Vaid and H. A.
Musallam, J. Org. Chem., 1987, 52, 150–153.
29 R. M. Moriarty, R. Penmasta, A. K. Awasthi, W. R. Epa and I.
Prakash, J. Org. Chem., 1989, 54, 1101–1104.
30 P. Finkelstein, J. C. Reisenbauer, B. B. Botlik, O. Green, A. Florin
and B. Morandi, Chem. Sci., 2023, 14, 2954–2959.
31 J. C. Reisenbauer, O. Green, A. Franchino, P. Finkelstein and B.
Morandi, Science, 2022, 377, 1104–1109.
32 J. C. Reisenbauer, A.-S. K. Paschke, J. Krizic, B. B. Botlik, P.
Finkelstein and B. Morandi, Org. Lett., 2023, 25, 8419–8423.
33 B. B. Botlik, M. Weber, F. Ruepp, K. Kawanaka, P. Finkelstein and
B. Morandi, Angew. Chem. Int. Ed., 2024, e202408230.
34 P. Spieß, M. Berger, D. Kaiser and N. Maulide, J. Am. Chem. Soc.,
2021, 143, 10524–10529.
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